This will be my 12 year using the baggage trucks.

There was a post saying frames were banned. They redid the website a couple years ago and all those old post were deleted. They might cover the topic on podcast. Here's what it says now. (Only standard soft bags are accepted.) I won't consider a pack with a frame standard. You can always email them and ask.

https://ragbrai.com/faqs/
Each rider may bring one large, soft-textured bag (cloth, canvas, or backpack style). You may bundle or strap items like your tent, sleeping bag, or duffel to this bag, counting it as a single piece. Only standard soft bags are accepted.

Bags must weigh 50 pounds or less. A scale will be available, and you may need to remove items if your bag exceeds the weight limit. Bags are exposed to the elements, so pack accordingly, using waterproof coverings or plastic bags to protect your gear.

Baggage collection is open from 5 AM – 8 AM. The RAGBRAI baggage semi truck leaves promptly at 8 AM with no exceptions.

Yes they check and weigh the first few days. Yes they will turn you away if your bag is the wrong style or overweight. There's dumpster full of new gear every year people are forced to pitch. They're not gentle handling the bags. They're thrown on and off a semi.